Saturday, August 28, 2010

What Causes Mudslides?

Mudslides can occur at any time of the year, regardless of weather conditions, according to the Federal Emergency Management Agency (FEMA). And they can strike without any prior warning signs, making for a dangerous phenomenon.

"Mudslides occur in all 50 U.S. states and can happen at any time – with or without rainfall," said Lynn Highland, a geographer at the USGS National Landslide Center.

Earthquakes, volcanic eruptions, changes in groundwater levels, alternate freezing and thawing, and the steepening of slopes by erosion all contribute to mudslides.

Construction and reckless modification of land – such as not draining an area properly before building on or near it – can also create the conditions ripe for a mudslide, Highland said.

She added, prolonged, intense precipitation and run-off can contribute to landslides, as can wildfires. Fires lead to mudslides because burning can kills the plants' roots. Roots hold soil together, stabilizing the land and making it less likely to be swept away, according to Highland. In this way, overgrazing can also contribute to mudslides.

Because different areas of land have different soil compositions, as well as varying slopes and geographic characteristics, it is difficult to determine how prone a place is to mudslides and therefore near impossible to predict when one will hit – although they are known to occur in areas previously hit by mudslides, according to the USGS.

"The West Coast is especially susceptible to mudslides because of the earthquakes, rainfall and wildfires that happen in that region," Highland told Life's Little Mysteries. "In California, there is a 'mudslide season' lasting from December to April, during which time the rainfall is fairly predictable."

Because California wildfires leave behind charred slopes, the region is especially susceptible to mudslides during and immediately after major rainstorms. However, sometimes damage caused by a mudslide can take days or even weeks to surface.

An example of this 'delayed triggering' of deeper landslides occurred in Los Angeles, Calif., in 1998, when mudslides forced the evacuation of more than 100 people and destroyed several houses five days after the rain had stopped, according to the California Geological Survey (CGS).

More than 100 Californians have been killed by land and mud slides during the last 25 years, according to the CGS. Most of these deaths were due to people being buried by debris flows as they slept in lower-floor bedrooms that were near hazardous slopes.
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Saturday, August 7, 2010

Textile Related to Earth: Geotextiles

As its name suggests Geotextiles refers to textiles related to earth or soil. When any permeable material used with rock, soil or earth it is termed as Geotextiles. The basic function of this technology is to prevent soil erosion to strengthening heavy concrete structures. This technology has not yet gained much attention in India, but is widely used in many countries for construction of bridges, roads, railway tracks to improve its strength. Many researchers have view that this technology is not newly developed but is in use from past thousands of years.

Formation of Geotextiles

Geotextiles can be formed of synthetic fibers, natural fibers or combination of the two. In past Geotextiles were made of natural plant fibers while today are usually formed of synthetic polymers such as polyester, polypropylene (PP), polyamides (PA) and polyamides (PA). Geotextiles made from natural fibers are less durable as they get decomposed with passage of time.

Choice of formation depends on the required properties and service life for which it is used. For example, natural fiber base Geotextiles is used for erosion control mats where durability is not a critical factor.

Natural Fiber Based Geotextiles

Natural fibers like Jute and coir have special applications. These different fibers degrade at different rates. Coir geotextiles degrade in 2 to 3 years while jute degrades in 1 to 2 years. Because of this property coir is used in situations where vegetation takes longer to establish, and jute is used in low rainfall areas as it can absorb more moisture. Also used for rural unpaved roads.


1. Natural fiber-based geotextiles are environmental friendly.

2. Its biodegradable nature has certain cost-effective applications in erosion control and re-vegetation.

3. It is helpful in quick establishment of vegetation.

4. It also helps in dust control, sand dune formation, wind erosion control and stabilization.

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